Pyrometer.



No. 890,895. Y PATENTED JUNE 16, 1908. G. FERY.

PYRO METER.

APPLICATION FILED APR. 1.1907.

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' Wd'n. e Asses No. 890,895. I PATENTED JUNE 16, 1908.

G. FERY.

PYRO METER.

APPLIOATION IILBD APR.1.1907.

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0. FERY. PYROMETER.

APPLIOATION I'ILED APR, 1. 1907.

PATENTED JUNE 16, 1908.

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the use of auxiliary ap aratus.

To all whom it may concern:

UNITED sTATEs PATENT oEEroE- CHARLES FERY, or PARIS, FRANCE.

PYROMIETER.

Patented June 16, 1968.

Application filed April 1, 1907. Serial No. 365,774.

Be it known that I, CH RLES FERY, a citizen of the French Republic, residing at Paris, in France, have invented certain new and useful Improvements in Pyrometers, of which the following is a specification.

This invention relates to pyrometers or temperature-measuring devices which utilize the radiant energy emitted by a hot body as a basis for the measurement of the temperature of that body.

According to this invention radiation proceeding from a hot body is focused by the action of a suitable member such as a convex lens or concave mirror upon an expansible body, and means are provided for indicating the amount of the ex ansion of such body which is ameasure of t e temperature of the hot body. Thus a pyrometer according to this invention is complete in itself without The indicating means are prefera ly such that the expansion of the body is made apparent upon a magnified scale; for instance, a li ht pointer ma be employed, or one of t e usual metho s of magnifying motion by means of a beam of light on a scale.

The body Which expands when heated by the radiation from the hot body is preferably of metal; for example, two thin strips of dissimilar metals may be soldered to other and formed into a flat spiral of the kim generally known as Breguets spiral. Such a spiral either becomes partly untwisted or twists up further when its temperature is raised.

In the accompanying drawings, Figure 1 is a longitudinal section of one form of pyrometer according-to this invention; Fig. 2 is a section on the line 22 of Fig. 1 to an enlarged scale; Fig. 3 is a perspective view of the strip and members attached thereto, and Fig. 4 1s a longitudinal section of part of a modified form of apparatus also according to this invention. Flg. 5 is a sectional view of part of the apparatus showing an adjusting device; Figs. 6, 7 and 8 illustrate diagrammatically means for rendering visible any want of accuracy in the focusing; and Fi s. 9 and 10 are respectively an elevation an a part longitudinal section showing asector dia hragm.

ith reference first to Fig. 1, A and B are cylindrical tubes forming the body of a telescope and capable of sliding one within the other for the purpose of adjustment of focus through the action of a rack and pinion M.

The front tube A carries a lens C at the conjugate focus whereof there is a body whose temperature is to be measured.

At the second conjugate focus is a multimetallic spiral strip D of the kind hereinbefore mentioned, consisting of two metals uneol ually si ver. The spiral D is preferably very minute so that it is capab e of being well covered by the image of a body of moderate dimensions. For example, dimensions which have in practice been found suitable for the spiral are as follows-The bimetallic strip from which the spiral is to be formed has a len th of about 1 cm., a breadth of 1mm.-, an a thickness of 0.02 mm.

The s iral D is coated with a substance such as amp black which absorbs radiation falling upon it. It has its inner extremity soldered to a small rod E of metal such as silver 01' cop er having a high conductivity for heat, an this rod is in turn fixed to a plate F to which is .attached an index or pointer G. The plate F is blackened on the side resented to the spiral D and brightly polis ed on the op osite side. The radiation which enetrates etween the turns of the spiral is thus received either by the turns or by the plate F which imparts by conduction to the spiral.

This plate may for convenience be termed a screen, although it has a dual function for it 'not only receives the rays which pass through the field of the expansible body, absorbs the same and transmits the heat by conduction to the body, but it also screens the body from direct rays as in Fig. 4 and from .rays reflected from the rear of the easing, as in Fig. 1. The screen should be ofan area approximately the same as the area of the ex ansible body and located on the side of the ody remote from the focusing means expansible, such as platinum and in order that the body may as far as possible be acted on directly by the focused rays.

The outer extremity of the spiral 1s firmly attached to a sup ort H preferably of a sub-- The index G can move over an are I which is suitably graduated and which thus indicates the temperature of the spiral and enables a calculation of the temperature of the hot body to be made in accordance with the known laws of radiation. It is preferred to graduate the arc I so that the temperature of the hot body under examination is read ofi directly without the need for calculation. For the purpose of effecting such a graduation of the arc, substances having known melting points may be,made use of, or the pyrometer may be compared with a standard pyrometer. The a aratus is com leted by an eye-piece J an has thus the orm of a telescope. By looking through the eyepiece, the observer is enabled to judge when the instrument is correctly sighted and focused, and at thesame time to read off the required temperature upon the graduated arc.

In order to eliminate errors which might otherwise arise from changes in the tem erature of the ap aratus as a whole, an a instment is provided whereby a small disp acement can be given to the graduated are I. The observer is thus able to insure that when no appreciable radiant energyenters the telesco e, the reading of the index G upon the arc is neither too high nor too low. Or insteadof making the are I adjustable, the su port carr ing the index G may be adjustable. An adjustment of this nature is illustrated by way of example in Fig. 5, where the support H carrying the index G or arc I isshown rovided with a feather H workin in a slot 1 in the tube B. A screw is forme at the extremity of the support and furnished with a nut H which can be tightened up to clamp the support H at any given point in the slot B Alternatively,'instead of the index G and are I being observed from the eye-piece J, the index may be made longer so as to be read against a graduated arc of correspondingly greater radius. An example of this construction is illustrated in Fig. 4 of the drawings where the tube B of the body of the apparatus is provided with a chamber K for the accommodation of the pointer G and are I. Some portion of the chamber is made of glass as at L, so that the scale-reading indicated by the pointer G can be readily seen. This construction in Fig. t also illustrates the employment of a concave mirror N instead of the convex lens C. The rack and pinion M are provided, as in the construction shown in Fi 1, and the eyepiece J 'mounted in a sma I draw tube 0, is placed in an opening at the center of the concave IIlllIOI.

Although the ex ansible body has been described as in the orm of a bimetallic strip, it is to be understood that any suitable expansion device having a receptive or sensitive portion of sufficiently small dimensions and capable of indicating temperaturechanges upon a suitably open scale may be emplo ed. Further, the apparatus may be grovi ed with a sector diaphragm or with evices for rendering any want. of accuracy in the focus readily visible; such features are known in the art and do not form in themselves part of the present invention, however, for the sake of clearness they are illustrated diagrammatically in Figs. 6 to 10 of the accompanying drawings.

Fi 6 illustrates a device for rendering read' y visible a want of accuracy in the focusing. Two pieces of plane mirror N and O are arranged nearly but not quite in the same plane, the line in which their planes intersect being the line a-b which 1s per endicular to the edges N N and 0 0 T ese mirrors N and O are placed as nearly as possible in the plane where the ima e is to be formed, the bimetallic strips, or ot er expansion device, occupying the central space P where the mirrors are cleared away so as to leave an aperture. Light reaching the mirrors N O is reflected back into the eye piece J Fig. 1, and when the object viewed is not focused in the plane approximately common to-the two mirrors ima es seen by reflection in those mirl ors, instea of blending to ether to form an unbroken image, as at R in ig. 7, appear displaced as at R in Fig. 8.

igs. 9 and 10 show a sector diaphragm used in conjunction with a pyrometer of the type shown in Fig. 1 of the drawin s. In front of the lens C is a diaphragm S aving sector-like apertures S S. The radiations entering the instrument are reduced, the

amount of such radiations being proportional to the angular width of the apertures Sf S As before intimated, the roportions' of the exposed field of the expanslble body and the image formed at the conjugate focus should be such that the imagealways covers the. exposed field of the expansible bod even when the object the temperature of w 'ich is to be measured is a relatively great distance away, for it is only when.such relation exists that a uniformity of the heating of the expansible body can be effected and a correct temperature reading secured without regard to the distance of the heated object, thus in accordance with well known laws and with proper focusing the image of a near object being large, a smaller pro ortion of. the rays emanating therefrom wi 1 be eflective in heating the expansible body, and as the distance of the ob ect increases the image rows smaller and an increased r0 ortion or the rays are concentrated in t e eld of the expansible body'and are effective in heating the same.

What I claim as my invention and desire to secure by Letters Patent is 1. A self contained portable pyrometer utilizing for the measurement of temperature the heating effect of the focused radiation emittedby a hot object, the combination may be determined, body formed of metals having different coefficients of expansion cated at the focus and exposed to the focused radiation, and an indicator mechanically connected for operation by the ex ansion and contraction of said body, said bo y having a field exposed to the radiation, of less area than the area of the image of the hot object when the radiation is focused on the body.

2. In a yrometer utilizing for the measurement o the temperature the heating ef- -fect of the-focused radiation emitted by a hot.

object,the combination with means for focusing the rays of -radiant energy, a body formed of metals having different coeflicients of ,expansion located at the focus of the rays,

' an indicator mechanically connected for operation by the expansion and contraction of said body, and means whereby. the focused rays passing through the field in which the body is ex osed are absorbed and transmitted to theody by conduction.

nected with and heated by conduction from said shield.

' 1. In a' yrometer utilizing for the measurement 0 term erature the heating effect of the focused ra iation emitted by a hot object, the combination with means for focusingthe rays of radiant energy, a shield located at the focus of the rays and having one face'absorbent and the other reflecting, and

a temperature indicating device associated withand screened by said shield from the action of rays other than-those concentrated in the field of the indicatin device.

'5. In a pyrometer ut zing for the measurement of tem erature the heating effect of this focused ra 'ation emitted by a hot object, the combination with means for focusmg the rays of radiant ener an expansible body located at the focus of i%e rays, an indicator controlled thereby, and a shleld located in proximity to the expansible body on the side thereof removed from the focusing means, said shield having an area of a proximateliyllthe area of the expansible b0 y.

6. a yrometer utilizing for the measurement of tem erature the heating effect of the focused radiation emitted by a hot ,body, the combination with a casing, a focusing element carried at one end of said casing, a

' multimetallic spiral strip within said casing,

a pointer Within said casin operatively connected with the strip, a sea e upon which the movement of the pointer is mdicated and means for adjusting said ointer and scale relatively to each other; su stantially as de- Q scribed.

7. In a yrometer utilizing for the measurement 0 temperature the heating efiect of the focused radiation emitted by a hot body, the combination of a concave mirror, a multimetallic spiral strip, a fixed sulpport where'- to one extremity of the spira stri is at tached, a short metal rod attache to the other extremit of the spiral strip, a metal plate mounte on the rod approximately parallel to the plane of the splral, a ointer attached to the metal plate, and a sea e upon which the movement of the pointer is indicated.

In testimony whereof I have signed my name to this specification in the presence of two subscribing witnesses.

CHARLES FERY.

Witnesses:

CHARLES PITAL, DEAN B. MASON. 

